- ID:
- ivo://CDS.VizieR/J/ApJ/817/10
- Title:
- Star-forming z~2.1 galaxy metallicities
- Short Name:
- J/ApJ/817/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the evolution of the Stellar Mass-Star Formation Rate (SFR)-Metallicity relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90<z<2.35. We present the galaxies' rest-frame optical emission-line fluxes derived from IR-grism spectroscopy with the Hubble Space Telescope and combine these data with SFRs and stellar masses obtained from deep, multi-wavelength (rest-frame UV to IR) photometry. We then compare these measurements to those for a local sample of galaxies carefully matched in stellar mass (7.5<~log(M_{star}_/M_{sun}_<~10.5) and SFR (-0.5<~log(SFR)<~2.5 in M_{sun}_/yr). We find that the distribution of z~2.1 galaxies in stellar mass-SFR-metallicity space is clearly different from that derived for our sample of similarly bright (L_H{beta}_>3x10^40^erg/s) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above ~10^9^M_{sun}_ and SFRs above ~10M_{sun}_/yr, the z~2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/645/A87
- Title:
- Star-galaxy classification feature importance
- Short Name:
- J/A+A/645/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Future astrophysical surveys such as J-PAS will produce very large datasets, the so-called "big data", which will require the deployment of accurate and efficient machine-learning (ML) methods. In this work, we analyze the miniJPAS survey, which observed about ~1deg^2^ of the AEGIS field with 56 narrow-band filters and 4 ugri broad-band filters. The miniJPAS primary catalog contains approximately 64 000 objects in the r detection band (mag_AB_<~24), with forced-photometry in all other filters. We discuss the classification of miniJPAS sources into extended (galaxies) and point-like (e.g., stars) objects, which is a step required for the subsequent scientific analyses. We aim at developing an ML classifier that is complementary to traditional tools that are based on explicit modeling. In particular, our goal is to release a value-added catalog with our best classification. In order to train and test our classifiers, we cross-matched the miniJPAS dataset with SDSS and HSC-SSP data, whose classification is trustworthy within the intervals 15<=r<=20 and 18.5<=r<=23.5, respectively. We trained and tested six different ML algorithms on the two cross-matched catalogs: K-nearest neighbors, decision trees, random forest (RF), artificial neural networks, extremely randomized trees (ERT), and an ensemble classifier. This last is a hybrid algorithm that combines artificial neural networks and RF with the J-PAS stellar and galactic loci classifier. As input for the ML algorithms we used the magnitudes from the 60 filters together with their errors, with and without the morphological parameters. We also used the mean point spread function in the r detection band for each pointing. We find that the RF and ERT algorithms perform best in all scenarios. When the full magnitude range of 15<=r<=23.5 is analyzed, we find an area under the curve AUC=0.957 with RF when photometric information alone is used, and AUC=0.986 with ERT when photometric and morphological information is used together. When morphological parameters are used, the full width at half maximum is the most important feature. When photometric information is used alone, we observe that broad bands are not necessarily more important than narrow bands, and errors (the width of the distribution) are as important as the measurements (central value of the distribution). In other words, it is apparently important to fully characterize the measurement. ML algorithms can compete with traditional star and galaxy classifiers; they outperform the latter at fainter magnitudes (r>~21). We use our best classifiers, with and without morphology, in order to produce a value-added catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/514/A3
- Title:
- Star-galaxy separation in AKARI FIS All-Sky Survey
- Short Name:
- J/A+A/514/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To separate stars and galaxies in the far infrared AKARI All-Sky Survey data, we have selected a sample with the complete color information available in the low extinction regions of the sky and constructed color-color plots for these data.We looked for the method to separate stars and galaxies using the color information. We performed an extensive search for the counterparts of these selected All-Sky Survey objects in the NED and SIMBAD databases. Among 5176 selected objects, we found 4272 galaxies, 382 other extragalactic objects, 349 Milky Way stars, 50 other Galactic objects, and 101 sources detected before in various wavelengths but of an unknown origin. 22 sources were left unidentified. Then, we checked colors of stars and galaxies in the far-infrared flux-color and color-color plots.
17844. StarHorse data for 5 surveys
- ID:
- ivo://CDS.VizieR/J/A+A/638/A76
- Title:
- StarHorse data for 5 surveys
- Short Name:
- J/A+A/638/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine high-resolution spectroscopic data from APOGEE-2 survey Data Release 16 (DR16) with broad-band photometric data from several sources, as well as parallaxes from Gaia Data Release 2 (DR2). Using the Bayesian isochrone-fitting code StarHorse, we derive distances, extinctions and astrophysical parameters for around 388,815 APOGEE stars, achieving typical distance uncertainties of 6% for APOGEE giants, 2% for APOGEE dwarfs, as well as extinction uncertainties of 0.07mag when all photometric information is available, and 0.17mag if optical photometry is missing. StarHorse uncertainties vary with the input spectroscopic catalogue, with the available photometry, and with the parallax uncertainties. To illustrate the impact of our results, we show that, thanks to Gaia DR2 and the now larger sky coverage of APOGEE-2 (including APOGEE-South), we obtain an extended map of the Galactic plane, providing an unprecedented coverage of the disk close to the Galactic mid-plane (|ZGal|<1kpc) from the Galactic Centre out to RGal 20 kpc. The improvements in statistics as well as distance and extinction uncertainties unveil the presence of the bar in stellar density, as well as the striking chemical duality in the innermost regions of the disk, now clearly extending to the inner bulge. We complement this paper with distances and extinctions for stars in other public released spectroscopic surveys: 324,999 in GALAH DR2, 4,928,715 in LAMOST DR5, 408,894 in RAVE DR6, and 6,095 in GES DR3.
- ID:
- ivo://CDS.VizieR/I/349
- Title:
- StarHorse, Gaia DR2 photo-astrometric distances
- Short Name:
- I/349
- Date:
- 05 Jan 2022
- Publisher:
- CDS
- Description:
- Combining the precise parallaxes and optical photometry delivered by Gaia's second data release with the photometric catalogues of Pan-STARRS1, 2MASS, and AllWISE, we derived Bayesian stellar parameters, distances, and extinctions for 265 million of the 285 million objects brighter than G=18. Because of the wide wavelength range used, our results substantially improve the accuracy and precision of previous extinction and effective temperature estimates. After cleaning our results for both unreliable input and output data, we retain 137 million stars, for which we achieve a median precision of 5% in distance, 0.20mag in V-band extinction, and 245K in effective temperature for G<=14, degrading towards fainter magnitudes (12%, 0.20mag, and 245K at G=16; 16%, 0.23mag, and 260K at G=17, respectively). We find a very good agreement with the asteroseismic surface gravities and distances of 7000 stars in the Kepler, K2-C3, and K2-C6 fields, with stellar parameters from the APOGEE survey, and with distances to star clusters. Our results are available through the ADQL query interface of the Gaia mirror at the Leibniz-Institut fuer Astrophysik Potsdam (gaia.aip.de) and as binary tables at data.aip.de. As a first application, we provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps as a function of distance, and extensive density maps. These demonstrate the potential of our value-added dataset for mapping the three-dimensional structure of our Galaxy. In particular, we see a clear manifestation of the Galactic bar in the stellar density distributions, an observation that can almost be considered direct imaging of the Galactic bar.
- ID:
- ivo://CDS.VizieR/I/354
- Title:
- StarHorse2, Gaia EDR3 photo-astrometric distances
- Short Name:
- I/354
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a catalogue of 362 million stellar parameters, distances, and extinctions derived from Gaia's Early Data Release (EDR3) cross-matched with the photometric catalogues of Pan-STARRS1, SkyMapper, 2MASS, and AllWISE. The higher precision of the Gaia EDR3 data, combined with the broad wavelength coverage of the additional photometric surveys and the new stellar-density priors of the StarHorse code, allows us to substantially improve the accuracy and precision over previous photo-astrometric stellarparameter estimates. At magnitude G=14 (17), our typical precisions amount to 3% (15%) in distance, 0.13mag (0.15mag) in V-band extinction, and 140K (180K) in effective temperature. Our results are validated by comparisons with open clusters, as well as with asteroseismic and spectroscopic measurements, indicating systematic errors smaller than the nominal uncertainties for the vast majority of objects. We also provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps, and extensive stellar density maps that reveal detailed substructures in the Milky Way and beyond. The new density maps now probe a much greater volume, extending to regions beyond the Galactic bar and to Local Group galaxies, with a larger total number density. We publish our results through an ADQL query interface (gaia.aip.de) as well as via tables containing approximations of the full posterior distributions. Our multi-wavelength approach and the deep magnitude limit render our results useful also beyond the next Gaia release, DR3.
17847. Stark broadening
- ID:
- ivo://CDS.VizieR/J/A+AS/113/579
- Title:
- Stark broadening
- Short Name:
- J/A+AS/113/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables of Stark broadening profiles for the N V 6f, g, h-7f, g, h, i line complex at 4945A have been generated. Modern close-coupling techniques are used for the electron broadening while the important influence of perturbing ions is included within the framework of the model microfield method. Comparison has been made with the results of line formation calculations using approximate formulae for the Stark profiles.
- ID:
- ivo://CDS.VizieR/J/A+AS/105/245
- Title:
- Stark broadening Al XI and Si XII
- Short Name:
- J/A+AS/105/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/542/A75
- Title:
- Stark broadening for the HeI 492.2 line
- Short Name:
- J/A+A/542/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables contain the area normalized Stark broadened spectral profiles of the HeI 492.2nm line. Doppler effect has not been included in the profiles. The first column of each table is the wavelength detuning, measured in nanometers, from the unperturbed wavelength. The other columns give the spectral profiles for different cases of perturber mass and electron temperature. Each table contains the data for a fixed electron density, ranging from 10^20^m^-3^ to 10^24^m^-3^ in different tables. Data corresponding to four different reduced masses of the emitter perturber pair, {mu}, are given in each table. The values of {mu} given in the tables are {mu}=0.8, 2.0, 4.0 and 10.0, in units of the proton mass. For each case of {mu} the profiles for different electron temperatures are given in different columns. Each table has a head giving the electron density value, and the values of {mu} and temperature corresponding to each column.
- ID:
- ivo://CDS.VizieR/J/A+A/400/791
- Title:
- Stark broadening of Be III lines
- Short Name:
- J/A+A/400/791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a semiclassical perturbation method, we have calculated electron-, proton-, and ionized helium-impact line widths and shifts for 52 Be III multiplets as a function of temperature and perturber density. Electron temperatures are 10000K; 20000K; 50000K; 100000K; 200000K and 300000K and perturber densities are from 10^11^cm^-3^ up to 10^21^cm^-3^. The obtained results have been used for discussion of regularities and systematic trends along spectral series.